Remote-operated fuse



July 21, 1959 H. R. 'roMLlNsoN REMOTE-OPERATED FUSE Filed April 12, 1957mvENToR HENRY RTOMLINSQN @wfg ATTORNEY United States Patent Q 2,896,0sRMOTEOPRATED FUSE Henry ER. Tomlinson, Framingham, Mass. ApplicationApril 12, 1957, Serial No. 652,495 6 Claims. tcl. 2004413) This'invention relates to a protective device for electric circuitsprincipally in the nature of a fuse and particularly directed to causeoperation of the fuse to disrupt the electric circuit by means of aremotely located or extraneous fuse controlling device; the provision ofsuch a fuse whether or not dependency is placed upon the electricalconditions existing in the protected circuit; and the provision of thedevice as above stated either including a substantially conventionalfusible member in the fuse as in the prior art or lacking the same.

A further object and advantage of the invention resides in the provisionof means controlling the operation of the fuse to disrupt the flow ofelectricity in response to an electric pulse or current from acontrolling device such as a relay, a high temperature detector, or anyother device generally used to initiate interruption of flow ofelectricity for protection of life or property, wherein the controllingdevice is remotely located or extraneous with respect to the fuse itselfand the fuse itself may or may not be provided with a conventionaloverload fusible means.

Another object and advantage of the invention resides in the provisionof a fuse as above stated which may be operated in timed coordinationwith other protective equip-mentV in the same electric circuit, andparticularly with respect to coordination of a fusible device with thetime-current characteristics of other devices so as to increase theefficiency of the electric service by doing away with unnecessaryinterruptions to flow of electricity; and the provision of a device asabove stated for simultaneous operation of two or more fuses in responseto an electric current from the controlling device, as for instance in apolyphase system.

Other objects and advantages of the invention will appear hereinafter.

Reference is to be had to the accompanying drawings, in which Fig. 1 isa view in elevation of a fuse according to the present invention;

Fig. 2 is a longitudinal sectional view thereof illustrating the devicein current-conducting condition;

Fig. 3 is a view similar to Fig. 2 but showing the novel fuse in currentinterrupting position;

Fig. 4 is a view similar to Fig. 2 but illustrating the conventionalfuse disrupted; and

Fig. 5 is a longitudinal sectional view showing a modication.

The present invention has been illustrated as applied to a cartridgetype of use, the use of which is well known in the art. This fuseembodies a tube which is a nonconductor and may be made of liber orporcelain. Within tube 10 is a cylindrical liner of ber or othermaterial 11. Provided at the ends of this tube, there areelectricityconducting ferrules 12 and 14 which are adapted to bereceived in conventional current-carrying clips as is well known in theart. The ferrules 12 and 14 may be secured to the tube 10 in any desiredmanner as for instance by screw threads or the like; and the ferrule 12is provided with an end plug 16 threadedly connected with a cap or thelike 18 by which means the plug 16 can be adjusted longitudinally withrespect to tube 10.

Attached to the plug 16, there is a helical spring 20 within tube 10,and this is attached to a conducting arcing rod 22. There are exibleconductors 24 which electrically connect the arcing rod 22 with the plug16.

The arcing rod has connected thereto at its opposite end a main fuseelement 26 which fuses or melts upon overload to open the circuit, as iswell known in the art. As shown in Fig. 2, this fusible element 26carries a conductor, or conductors, 28 normally held in current-carryingrelationshipwith an interior, outwardly-haring, conical surface inferrule 14. y y

Attached to ferrule 14 by screw-threads or otherwise, there is aretaining cup generally indicated at 30 and this is provided withscreened windows 32 to allow for exit of gases'. 4The cu'p is used toconfine a retaining plug generally indicated at 34 having shoulder 36retaining a spring 38. The plug 34 is provided with a beveled end at 40normally holding the conductor 28 in good electrical contact to theinterior conical wall of the ferrule 14 as clearly shown in Fig. 2 andindicated at 42.

The plug 34 is axially bored and accommodates a restraining insulatinglink 44 which is connected to the fusible element 26. Link 44 is heldwith relation to plug 34 by means of an auxiliary vfusible element 46which may be pinned thereto and held by and between a pair of contactscrews 48 to which Yare connected leads 50. These leads are connected toapower supply or control circuit by which means Afuse 46 is to bedisrupted at the will of the operator or by .some other automaticcontrol means not specifically a part of the present invention.

It will be seen that the conducting arcing rod 22 is restrained frommotion due to the force of spring 20 by means of both the main fuseelement 26 and the auxiliary fuse element 46. The tensional force ofspring 20 seats the retainer plug 34 against the ferrule 14, thusclamping conductor 28 thereto against the action of spring 38. Theprotected electric circuit is 'made from the bottom clip ferrule,through conductor 28, fuse 26, rod 22, conductors 24, plug 16, cap 18and ferrule 12.

When current is applied to the auxiliary yfuse 46 by means of a relay orother remote device, not shown, sufiicient current passes throu-gh it tomelt the fuse completely and instantly, thus releasing the restraininglink 44 allowing spring 38 to move the plug 34 downwardly to the Fig. 3position. The conductor 28 and the arcing rod are thus released and thespring 20 immediately retracts and pulls the arcing rod 22 upwardly,definitely interrupting the circuit by removing the conductor 28 fromferrule 14. The plug 34 is retained in the cup 30 and the escapement ofgases generated by the arc passes through windows 32. The arcing rodtravels extremely fast and it breaks contact quickly.

However, the showing of Fig. 4 discloses how the main fuse 26 may bedisrupted by the existence of current passing through the fusesuiciently high to cause this fuse to melt. In this instance, the spring20 causes the arcing rod to move away from the conductor 28 and also ofcourse plug 34 is moved to the same position as in Fig 3. The auxiliaryfuse is still intact since no current has passed to cause this fuse toblow. Thus it will be seen that the auxiliary fuse is completelyextraneously controlled, but the main fuse operates as in the prior art,without change in its overload protection.

In Fig. 5 there is shown a modification of the inven tion wherein thereis no main overload fuse. In this case, the arcing rod 52 is directlyconnected with a fuse element 54 holding the rod in contact with springtype contacts 56 mounted internally on clip ferrule 58. The

3 other end of the fuse is the same as above described with reference toFigs. 1 to 4.

An insulating plate 60 holds the fuse 54 and a circuit 62 is connectedto melt the fuseupon the closing of switch 64 which maybe manual orrelay operated, etc. In this case, fusing of element 54 merely releasesthe arcing rod and it snaps up in the tube 10 as before, interruptingthe main circuit instantly.

Having thus described my invention and the advantages thereof, I do notwish to be limited to the details herein disclosed, otherwise than asset forth in the claims, but what I claim is:

1. A remote operated fuse comprising a fuse body, a pair of spacedmembers thereon forming electric contacts, a current-carrying movableelement to bridge said members, said movable element including a mainfusible element, a spring tending to move the element to electricallydisconnect said members, means including an auxiliary fusible element tohold the movable element in current-conducting position, a normally openelectric circuit connected to the auxiliary fusible element, and meansto close the circuit at will to fuse the fusible element and release themovable element.

2. A remote operated fuse comprising a fuse body, a pair of spacedmembers thereon forming electric contacts, a current-carrying movableelement to bridge said members, said movable element including a mainfusible element, a spring tending to move the element to electricallydisconnect said members, means including an auxiliary fusible element tohold the movable element in current-conducting position, a normally openelectric circuit connected to the auxiliary fusible element, and meansto close the circuit at will to fuse the fusible element and release themovable element, said main fusible element being disrupted by overloadin the current passing through the movable element, and the auxiliaryfuse being electrically separated therefrom so that it is unaffected bythe disruption of the main fusible element.

3. In a remote operated cartridge fuse of the type described includingan insulative cylinder mounting clip, ferrules at the ends thereof witha tension spring associated with one ferrule and a movable arcing rodconnected to the spring and tensioning the same in position of thearcing rod to conduct current between the ferrules, that improvementcomprising a fusible element connectible with respect to the arcing rodand holding it inoperative current conducting condition, and a separateelectric current carrying circuit operatively connected with respect tothe fusible element and including a circuit closing device for fusingthe fusible element to release the arcing rod for movement to currentdisruptive con dition, a separate fusible element, the latter beingconnected between the rst fusible element and the arcing rod andnormally carrying the current between the ferrules. I

4. A fuse comprising a hollow body, a ferrule at each end thereof, oneferrule being hollow and having an interior surface flaring outwardly,an arcing rod in the body, resilient means to move the rod in onedirection, a conductor secured to the rod, fusible means to hold the rodwith the conductor contiguous to the interior surface of the said oneferrule against the action of the resilient means, a retaining memberhaving a surface complementary to the flaring surface, said fusiblemeans being mounted in the retaining member and holding the sameyieldingly in position to clamp the conductor against said flaringsurface.

5. The fuse of claim 4 wherein the said fusible means is insulated fromthe ferrules and the arcing rod, and including means to melt the fusiblemeans.

6. The device of claim 1 wherein said last-named means includes atransformer.

References Cited in the file of this patent UNITED STATES PATENTS1,294,621 Conrad Feb. 18, 1919 1,977,191 Levenstein Oct. 16, 19342,087,744 Triplett July 20, 1937 2,315,678 Wallace Apr. 6, 19432,481,298 Eldridge Sept. 6, 1949 2,485,076 Timerman Oct. 18, 19492,683,201 Miller et al. July 6, 1954 2,757,259 Cruse July 31, 19562,762,884 Van Eyk Sept. 11, 1956

